NUCLEAR CRATERS AND PRELIMINARY THEORY OF THE MECHANICS OF EXPLOSIVE CRATER FORMATION
Four nuclear craters were produced at the Nevada test site. Three were from 1.2-kiloton nuclear explosions in desert alluvium, a sand-gravel mix, and the fourth was from a 115-ton nuclear explosion beneath the sloping side of a bedded tuff mesa. Comparison of these craters with high-explosive craters in alluvium shows that, within experimental error, the craters produced by subsurface nuclear explosions are quite comparable with those produced by equal yield chemical explosions. Experimental data from these nuclear and chemical explosive cratering programs and theoretical machine calculations of the behavior of underground explosives make it possible to construct a picture of the major mechanisms that contribute to the formation of explosion craters. These mechanisms include compaction and plastic deformation of the medium imiately surrounding the explosion, spalling of the surface above the explosion by the tensile wave generated at the free surface of the ground, and acceleration of the fractured material overlying the explosion cavity by the gases trapped in the cavity, before and during their escape. The role that each mechanism plays changes with the scaled depth of burst of the explosive and to some extent with material. The contribution that each makes is outlined for four typical craters representing surface, shallow, optimum, and deep burial depths. For surface burial, plastic deformation and compaction are the principal actions; for shallow burial depth, spall is the dominant feature; for optimum depth, gas acceleration becomes the most important mechanism; and for deep burial, subsidence into the cavity produced by plastic deformation and compaction is the major factor. The differences to be expected between explosion craters and craters resulting from impact explosions such as those produced by meteors are examined. The relative contribution of each of these mechanisms is also estimated for apparent crater depth vs. depth of burst. (auth)
- Research Organization:
- Univ. of California, Livermore
- NSA Number:
- NSA-16-000411
- OSTI ID:
- 4836727
- Report Number(s):
- UCRL-6481
- Journal Information:
- J. Geophys. Research, Journal Name: J. Geophys. Research Vol. Vol: 66
- Country of Publication:
- United States
- Language:
- English
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